FIG. 1 illustrates an architecture of the existing Long Term Evolution (LTE) mobile communication system.
Referring to FIG. 1, the radio access network of the LTE mobile communication system is composed of a user equipment (UE) 100, an evolved base station (Evolved Node B, RAN node, eNB or Node B) 105, Mobility Management Entity (MME) 110, Serving Gateway (S-GW) 125, Packet Data Network Gateway (PDN-Gateway, P-GW) 130, Application Function (AF) 140, and Policy and Charging Rules Function (PCRF) 135. The UE 100 may connect to an external network through the ENB 105, S-GW 125 and PDN Gateway (P-GW) 130. The radio access network may further include or be connected with entities/systems such as Universal Terrestrial Radio Access Network (UTRAN) 180, GSM EDGE Radio Access Network (GERAN) 190, Serving GPRS Support Node (SGSN) 115, and Home Subscriber Server (HSS) 120.
The UE 100 may connect to an external network such as operator IP service 150 through the ENB 105, S-GW 125 and P-GW 130. The AF 140 is an entity that exchanges application related information with the user at an application level. The PCRF 135 is an entity for controlling policies related to user QoS (Quality of Service). Policy and charging control (PCC) rules corresponding to a specific policy are sent to the P-GW 130 for enforcement.
The ENB 105 is a radio access network (RAN) node, which corresponds to Radio Network Controller (RNC) of the UTRAN 180 or Base Station Controller (BSC) of the GERAN 190. The ENB 105 is connected with the UE 100 through a wireless channel and functions similarly to the existing RNC or BSC.
In the LTE system, as all user traffic including real-time services like VoIP (Voice over IP) services is served by shared channels, it is necessary to perform scheduling on the basis of status information collected from UEs 100. The ENB 105 performs this scheduling function.
The S-GW 125 provides data bearers, and creates and removes a data bearer under control of the MME 110. The MME 110 performs various control functions, and may be connected to multiple ENBs 105.
The PCRF 135 is an entity performing overall QoS and charging control functions for traffic.
In general, User Plane (UP) refers to a path involving the UE 100, ENB 105, S-GW 125 and P-GW 130, along which user data is sent and received. In this path, wireless channels with severe resource constraints are used between the UE 100 and ENB 105.
In a wireless communication system like LTE, QoS is applied on an Evolved Packet System (EPS) bearer basis. One EPS bearer is used to transmit IP flows having the same QoS requirements. QoS parameters such as QoS Class Identifier (QCI) and Allocation and Retention Priority (ARP) may be assigned to an EPS bearer. EPS bearers correspond to Packet Data Protocol (PDP) contexts of the General Packet Radio Service (GPRS) system.
The RAN has to exchange data with users within limited frequencies. When many users remain in a cell managed by a RAN node (i.e. ENB 105) or the amount of user traffic becomes large, congestion may arise in the RAN. In a related art scheme for dealing with congestion, the ENB 105 may prioritize resource allocation using QoS parameters such as QCI or ARP values assigned to bearers.
However, with introduction of various types of service applications, multiple media or IP flows with different QoS requirements may be involved in a single service or application. For example, when different media such as text, photograph, video and music coexist with each other in a single webpage, the individual media may have different QoS requirements in the existing system. In the case of failure in integrated congestion control, one medium may be delivered earlier or later than another medium, degrading service quality perceived by the user. For example, video mapped with a bearer of high-precedence QCI may be received first, and text mapped with a bearer of low-precedence QCI may be received later, causing user inconvenience.